The ‘Ceona Amazon’ multi-function tie-back, field development and construction vessel is regarded as a game-changer capable of executing all aspects of deepwater projects in environmentally-challenging locations for keener logistic costs. By David Tinsley.

Investment in a cutting-edge, deepwater field development vessel by expansion-minded, London-based subsea contractor Ceona Services has received an early endorsement by way of a US charter for work in the Gulf of Mexico.

Based on a drillship hull design, and with main dimensions of 199.4m x 32.2m, the Ceona Amazon offers the capability for operating in multiple pipelay modes, and incorporates heavy-lift facilities and substantial underdeck and above deck carrying capacity.

The newbuild’s seakeeping characteristics facilitate deployment in remote and challenging locations. Besides rigid pipelay, the vessel is able to lay flexible pipelines and umbilicals, and install subsea structures using two 400te cranes singly or in tandem, to depths as great as 3,000m. The design is especially well suited to conditions off West Africa and Brazil and in the Gulf of Mexico.

The overarching theme behind Ceona’s new, diesel-electric flagship is a level of performance and self-reliance that allows demanding projects to be fulfilled in a single mobilisation, obviating the need for multiple vessels or trips. The company, a specialist in the SURF (subsea umbilicals, risers and flowlines) category, claims that the 33,000gt Ceona Amazon takes subsea construction and installation into a new era.

Her initial job, awarded by Walter Oil & Gas Corporation of Houston, embraces a major, rigid pipelay scheme. Within the compass of the Coelacanth Export Pipelines project, the ship is to put down oil and gas export lines tying the new Coelecanth platform into existing pipeline infrastructure. This will entail a total 11.6 miles (approximately 36km) of 10-inch line. In addition, Ceona Amazon is to install two pipeline end termination (PLET) structures for each pipeline. The complete assignment will be fulfilled in just one mobilisation.

Main contractor Lloyd Werft delivered the vessel on time and within budget less than two years after the letter of intent for construction had been signed. Huisman, a global leader in the design and manufacture of heavy construction equipment for onshore and offshore operations, pre-built the two masthead cranes and pipeline vertical lay system (VLS) ready for fitting at the Dutch company’s Schiedam quays following the vessel’s transfer from Lloyd Werft. The ship’s hull was built at Crist’s Gdynia premises in Poland under subcontract to the Bremerhaven yard, strengthening the co-operation between the two concerns and assisting Lloyd Werft in developing its strategy as a completion facility for high quality, special-purpose newbuilds.

The innovative G-lay pipe lay system, developed and patented by Ceona, features an inclinable lay spread with a top tension of 600te and a rigid firing line system. Rendering the vessel akin to a ‘floating factory’, in-situ assembly of rigid pipe joints is carried out along a traditional firing line. Once welded, the pipe is deflected around an 18m-diameter stern wheel and led up to the pipelay tower, culminating in vertical exit, in J-lay fashion, through the moonpool in bottom of the hull amidships.

So as to reduce the influence of vessel motions on pipe stresses during installation, the VLS tower and moonpool have been positioned close to the ship’s transverse axes. This should allow uninterrupted operation during relatively heavy seas and strong winds. Moreover, the moonpool has been sized (8m x 13.5m) to accommodate the largest PLETs.

Ceona Amazon has substantial capacity for both rigid or flexible pipe, or a mix of both, providing overall storage in the holds and on deck for a maximum 9,500te. The combination of high transport volume, multiple pipe lay operational modes and independence from a shoreside spool base, plus heavy-lift capability, imbues her with the scope to carry out all aspects of SURF projects. She can load sufficient quantities of rigid and flexible pipe, risers, umbilicals, and/or subsea structures to execute logistically complex assignments in remote environments in a single trip, potentially with no other vessel or barge support.

The twin Huisman 400te masthead cranes, using active heave compensation (AHC) to counter the ship’s vertical motions, are capable of operating in tandem to lower large subsea structures, as well as handling long subsea spools. Furthermore, the cranes can be used to support installation of mooring spreads for semi-submersibles, tension leg platforms (TLPs) and floating production, storage and offloading (FPSO) units. The outfit also allows dual crane upending of slender structures such as piles or tendon sections.

The cargo stowage available in the two 3,500te-capacity holds is augmented by space on the 4,600m2 open main deck, allowing additional storage of line pipe and standard flexible installation reels, as well as project-specific equipment. Underdeck provision has been made for 23m-diameter pipe carousels. The deepwater cranes, fitted on the port side of the working deck, are complemented by a 30te AHC knuckle boom crane.

The turnkey contract for all electrical work, as well as the integrated navigation, automation, communication, energy distribution and propulsion systems, including the entire cabling installation, was awarded by Lloyd Werft to SAM Electronics of Hamburg. The highly complex project adds to a raft of successes for L-3 Group company SAM Electronics in the offshore construction support vessel sector, complementing its high profile in the wider shipping market.

The vessel control system supplied to Ceona Amazon consists of a NACOS Platinum integrated navigation suite, featuring standardised workstations with multipurpose displays, and an MSC Platinum automated monitoring and control system. This is capable of handling approximately 4,500 input and output signals through 10 processing stations. Supplementary support facilities comprise a full range of internal communications plus GMDSS equipment.

Electrical power for the seven asynchronous thruster drives is generated by six diesel alternators feeding three medium-voltage switchboards. Other elements of the SAM Electronics ‘package’ include low-voltage 12-pulse and six-pulse PWM (pulse width modulation) converter drives, asynchronous motors, and 16 medium-voltage propulsion and distribution transformers.

The diesel-electric power and propulsion system is based on six main gensets, using common rail, four-stroke engines developed and manufactured by MAN Diesel & Turbo. Four of the aggregates have eight-cylinder 32/44CR diesels, while two are powered by nine-cylinder models of the same design, such that the total maximum output of the plant is 28,000kW.

Each engine was constructed at MAN’s Augsburg production complex in southern Germany, then transported to the company’s Frederikshavn site in northern Denmark for a full electrical test as a generator assembly before transfer to the shipyard in Bremerhaven.

Main propulsive force is delivered by three 3,500kW Steerprop azimuth thrusters at the stern, while three Brunvoll retractable thrusters, of 2,400kW apiece, and a Brunvoll 1,800kW tunnel thruster, are fitted in the bow. The asynchronous motors for the 3,500kW thrusters have a speed range of 0-900rpm, those serving the retractable thrusters cover 0-714rpm, while the transverse thruster motor has a range of 0-890rpm. The ship has been engineered to DP2 dynamic positioning standard, using a Kongsberg Maritime K-Pos system.

To keep the thruster drives independent from other influences, each propulsion transformer has been equipped by SAM Electronics with an extra low-voltage winding system, at 200kVA, to supply an auxiliary Motor Control Center (MCC). The MCC feeds all auxiliary elements of the related drive, such as the transformer, converter and motor fans and converter water cooling pumps.

In addition, each of the seven thruster drives is provided with an uninterruptible power supply (UPS) system for the associated 6,600V switchboard section and drive control. For subsystems such as speed and azimuth lever control, 110V DC is locally converted into 24V DC to minimise the voltage drop over long cable distances.

So as to limit the inrush current, a pre-magnetising circuit has been installed for each propulsion transformer. Before switching on the main circuit breaker, the auxiliary star coil of the transformer is energised via the auxiliary 440V MCC to induce a voltage with correct phase angle at the primary side. Furthermore, resistors have been fitted to reduce the inrush current values to within the nominal range.

All superstructure is arranged forward, wherein accommodation has been provided for a maximum crew and project complement of 200, in 16 single-berth and 92 double-berth cabins. The effectiveness of measures adopted to attenuate noise and vibration, in the interests of habitability, is implicit in the Harmony Class HC(3) notation conferred by DNV GL.

Creating a platform at a level of one deck above and forward of the navigation bridge, the requisite helicopter deck spans the bow and has been dimensioned for large craft such as the Sea-King S-61N and Sikorsky S-92.

Ceona Amazon is the second newbuild that Ceona has introduced to the market in less than a year. She was preceded by the deepwater pipelay and construction vessel Polar Onyx, under five-year charter from Norwegian owner GC Rieber Shipping. Built by Ulstein Verft, and embodying the proven X-Bow hull form for increased safety and power efficiency, Polar Onyx is equipped with a Huisman VLS and is currently engaged for pipelay operations in Brazilian offshore waters.

Backing for Ceona’s fleet development has been forthcoming from majority shareholder Goldman Sachs Capital Partners.